The invention concerns a group control for elevators with double cars which are arranged in a common car frame to serve two adjacent floors. The car calls for trips to floors which are located in the direction of travel ahead of the car in question, are subject to a limitation of operation which differentiates between two call groups. The first call group comprises calls for odd numbered floors of the upper car and calls for even numbered floors of the lower car, and the second call group comprises calls for even numbered floors of the upper car and calls for odd numbered floors of the lower car. The limitation of operation can be cancelled under certain predetermined conditions.
U.S. Pat. No. 3,625,311 discloses a control for an elevator group with double cars arranged in such a way that two adjacent floors can be served simultaneously. Thus, the full occupation of a building should be attained in the shortest possible time with approximately uniform occupancy of the double cars. Passengers at the ground floor for even numbered floors enter the upper car and for odd numbered floors enter the lower car, where in each case the car call generation circuits for the floors not assigned to the car are blocked. As soon as the car has to stop for a floor call, the blocking is cancelled, so that an added passenger for any desired floor can travel in an upward direction. Likewise it is possible for travelers, who have entered the wrong car at the ground floor, to still travel to the desired floor by repeated operation of the car call generator circuit, whereby the objective to fully occupy the building in the shortest possible time can hardly be achieved.
This prior art elevator control is also slowed down when a traveler does not make use of the elevator called by him. A further disadvantage of this control is, that in case a traveler enters at a stop due to a car call without operating the floor call circuit, the blocking is not cancelled, so that the car will not stop at the desired floor. The above described control uses cold cathode tubes in its car call circuits, which at the same time serve as a car call register (or memory). The blocking of these car call circuits takes place by interruption of the plate voltage, whereby the storage of the car calls is prevented. The latter fact can be considered a disadvantage, as the calls have to be entered again after cancellation of the blocking action.